At present, a general standard keyboard includes a plurality of rows of keys installed on a base, and each key represents a numeric character or a textual character. For example, the base used for an English input method is composed of four independent character keys “1, Q, A, Z” sequentially arranged from the left to the right of the first row, four independent character keys “2, W, S, X” sequentially arranged from the left to the right of the second row, and so on for the remaining rows (and the layout of a standard keyboard is a universal mode, and thus will not be described herein). However, each character of the installation mode of such keyboard occupies an independent key, and a gap between the independent keys is required for the partition purpose, so that the area of the standard keyboard cannot be reduced, and its weight must be increased. As a result, it is relatively difficult for users to carry the standard keyboard, particularly to those applied as a standard keyboard of a mobile phone. Although some mobile phones (such as blackberry) adopt the standard keyboard mode, yet the area of the keyboard is too large for an easy carry.
To overcome the aforementioned drawback, a “one-row keyboard and approximate typing” disclosed in U.S. Pat. No. 7,387,457 adopts the standard keyboard mode and includes a plurality of textual or numeric characters arranged in rows and installed to keys at different electric contact positions respectively, so that when a user presses a letter at a different key, a software is provided for combining the input into a corresponding character, but sometimes errors of the combination occur, and thus causing troubles to users, requiring the users to enter the letter again, and affecting the input speed. The aforementioned keyboard not wastes time only, but also causes operational troubles. Obviously it is not good for its intended application.
R.O.C. Pat. Publication No. 200723686 entitled “Composite-key keyboard, electronic device and character input method” discloses a keyboard having a plurality of composite keys installed on the keyboard, and the composite keys include a primary key and a subordinate key, and each primary or subordinate key represents a character, and the primary and subordinate keys are installed adjacent to each other and can be pressed individually or simultaneously provided for inputting a corresponding character. However, this structure sometimes requires users to press the primary and subordinate keys together, thereby wasting time, causing operational troubles, failing to comply with the standard keyboard installation and affecting the input speed. Obviously, it is not good for its intended application.